Investments (Details 1) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Held to maturity
Due in one year or less, Amortized Cost	$ 1,501,000
Due after one year through five years, Amortized Cost	33,764,000
Due after five years through ten years, Amortized Cost	4,969,000
Due after ten years, Amortized Cost
Residential mortgage-backed securities, Amortized Cost	180,000
Total held to maturity, Amortized Cost	40,413,865	42,100,196
Due in one year or less, Estimated Fair Value	1,507,000
Due after one year through five years, Estimated Fair Value	34,895,000
Due after five years through ten years, Estimated Fair Value	5,176,000
Due after ten years, Estimated Fair Value
Residential mortgage-backed securities, Estimated Fair Value	193,000
Total held to maturity, Estimated Fair Value	41,771,000	43,736,000
Available for sale
Due in one year or less, Amortized Cost	18,812,000
Due after one year through five years, Amortized Cost	69,953,000
Due after five years through ten years, Amortized Cost	197,455,000
Due after ten years, Amortized Cost	253,393,000
Residential mortgage-backed securities, Amortized Cost	124,301,000
Total available for sale, Amortized Cost	663,914,000
Due in one year or less, Estimated Fair Value	19,065,000
Due after one year through five years, Estimated Fair Value	72,469,000
Due after five years through ten years, Estimated Fair Value	209,715,000
Due after ten years, Estimated Fair Value	269,695,000
Residential mortgage-backed securities, Estimated Fair Value	126,504,000
Total available for sale, Estimated Fair Value	$ 697,447,513	$ 694,509,821